I would second that motion. Then again, changing the end cap can be done without removing the blades, IF done very carefully. Myself, I guarantee I will be searching the mud for parts. I have installed the Maxi Prop on my trimaran, yet to get it wet. Have the prop zinc, and a shaft zinc.
What I have not heard here is if anyone has contacted PYI to see if the end cap is available as a separate part. I realize there may be fitment problems, as the tolerances are very tight on the Maxi Prop, but it is worth a try.
I agree that the idea of helicoils might create additional problems. I would opt for larger hardware.

Rule number one for underwater Max Prop work, have a "safety net" under the prop to catch anything that might drop. I use a 3' X 3' square of PVC pipe with a mesh material stretched over it. It floats but zinc on a lanyard at each corner keeps it just above the bottom without my having to deal with a line hanging from the shaft getting in my way.

As far as removing the end cap goes, it cannot be done without removing the blades, as the blade/spindle assembly rides within the end cap. I hang a small mesh bag from the prop shaft for tools and the machine screws that I remove as I disassemble the prop. I loosen the last of the 6 screws that hold the end cap to the spinner halves until I can turn it by hand. Then with one hand on the cap to keep it in place I take out the last screw and put it in the bag. Then I have two hands free to deal with the cap and blades. Pulling the cap gently towards me with one hand, the other is making sure the blades come off with it, as a unit. Then I deposit the whole shebang on the dock.

Re-installing the cap and blades is a little more tricky, but not too difficult. It takes a rather deft movement to get the cap/blade assembly back into position on the spinner halves without losing anything. I have to hold the parts in position with one hand while moving the blades back and forth with the other hand to get the gears to mesh properly which allows the cap to fully seat against the spinner halves. Then, holding everything together with one hand I pick up a machine screw out of the mesh bag and get it started with the other. Then I can release the parts and begin installing the remaining screws. Probably sounds more complicated than it really is, but if I can do it, anybody can. Thorough familiarization with the Max Prop instruction manual is very helpful.

If anybody intends to attempt this, either underwater or in the yard, it is critical that the body of the prop be marked before disassembly while the blades are fully feathered. Then the hub and spinner halves can be returned to this position during reassembly and the blades moved to the feathered position before the end cap screws are tightened. This assures that the pitch is not altered during the procedure.

The small screws I believe were an enginering mistake. The two max props Iam aware of that use the small screws do not work for good contact. Electroalis is interesting. A owner that just changed his brand of zinc for the end cap all of a sudden one bolt does not tighten up. This is a prop Ive worked on for 4 years with no issues then bang. His has the the larger screw on the 63. Which is good.